1. Field of the Invention
The present disclosure is related to the liquid crystal display device and the driving method for selectively controlling the average picture level (or “APL”).
2. Discussion of the Related Art
Nowadays, in the display device market, for replacing cathode ray tube (or “CRT”) having heavy and large volume, various flat panels are developed. For these flat panel display device, there are liquid crystal display (or “LCD”) device, field emission display (or “FED”), plasma display panel (or “PDP”), electroluminescence device (or “EL”) and so on.
Thanks to the light weight, the thin thickness, the low power consumption, and the low power driving, the liquid crystal display device is progressively applied to various applications. For example, the liquid crystal display device is applied to the portable computer such as notebook PC, the office automation devices, the audio/video devices, the advertizing devices. The liquid crystal display device represents the video images by controlling the electric field supplied to the liquid crystal layer to modulate the light entering from the backlight unit.
As shown in the FIG. 1, as the LCD device has the driving characteristics in which the video image is represented with maximum brightness always regardless of the condition of the image contents, the peak brightness is almost equal to the full white brightness. The peak brightness is the brightness detected at the central portion of the LCD panel when the LCD panel is driven such that the back ground image of the LCD is represented with the black gray-scale and the central portion surrounded by the back ground is represented with the maximum brightness. The full white brightness is the brightness detected from the screen when the overall screen of the LCD panel is represented with the maximum brightness.
If the peak brightness is closely equal to the full white brightness, it is advantage for the computer monitor in which the exact brightness and color representation are important. However, for the television monitor of which video images are changed dynamically, this monitor may make a bad effect to the observer's eyes. Especially, when a person watches a snowy background of which most peak brightness is the white gray-scale, due to excessive high brightness, eye glare is getting severely and then eye fatigue will be accumulated.
On the contrarily, for the PDP or CRT, the full white brightness is generally lower than the peak brightness. Therefore, when watching high brightness image contents of the PDP or CRT, the brightness of each pixel will be naturally down so that the eye glare phenomenon is not occurred and the eye fatigue is lowered.
As a result, required are the method for reducing eye glare and eye fatigue when an LCD device shows a high brightness image contents.